Oscillograph



Feb. 10, 1931. J, w EGG 1,792,315

OS C ILLOGRAPH Filed Nov. 26, 1924 4 Sheets-Sheet l WITNESSE I INVENTOR l 74 74 Jox/@ M///U/d/,ygx

y l BY ATTORNEY-- Feb. 10, 1931. J. w. LEGG 1,792,315

l xjfli all/IW ATTORNEY Feb. l0, 1931. J. w. LEGG 1,792,315

oSfcILLoGRAPH Filed Nov. 2e, 1924 4 sheets-sheet 5 /f INVENTOR AT ORNEY J. W. LEGG Feb. 10, 1931.

OSCILLOGRAPH 4 Sheets-Sheet 4 F'iled Nov.

WITNESSES:

ATTORNEY Patented Feb. 10, 1931 UNITED STATES PATENT OFFICE JOSEP W. LEGG, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR T WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION 0F PENNSYLVANIA OSCILLOGRALPH Application led November 26, 1924. Serial No. 752,427.

My invention relates to oscillographs and particularly to oscillographs of the portable type.

One object of my invention is to reduce the size and weight of a portable oscillograph and to render the same simple, compact and durable in construction, economical to manufacture and effective in operation.

Another object of my invention is to proditions may be super osed effectivelyon one record sheet and rea ily distinguished from one another.

Another object of my invention is to so arrange the parts of an oscillograph as to permit the galvanometer element to have a relatively great lever arm in proportion to the size of the casing in which it is contained.

Another object of my invention is to provide means for compensating for discrepancies in the relative positions of a galvanometer mirror element and its light source.

Another object of my invention is to provide means whereby energization of the galvanometer and lamp circuits and the operation of a photographic chart may be definitelyl timed relative to each other.

Heretofore, in oscillographs or oscilloscopes, in which a `photographic chart and a polygon of mirrors have been employed for obtaining curves of the instantaneous values of the voltage, current and other characteristics of electric circuits, i-t has been'usual to employ a number of galvanometer elements corresponding to the number of circuits or characteristics to be simultaneously studied. This practice naturally resulted inthe production and usevof instruments of relatively large size and cost'.

It has, also, been usual to employ a casing of sufficient size to permit the optical lever arm or reflected light beam from a galvanometer mirror to extend uninterruptedly from the mirror to a shutter in a wall of the casing. This feature also necessitated the utilization of a casing of sufficient size to correspond to the angular deflection of the galvanometer element.

It is mfy aim to improve an oscillograph by so modi ying the above-mentioned features as to overcome certain objectionable features and to provide an instrument that shall be eX- tremely compact in construction and light inweigh-t and the manipulation of which shall be facilitated.

In practicing my invention, I rovide a galvonometer element and means or so rapidly changing it from one circuit to another that the human persistency of vision causes the element to appear to give simultaneous indications of different quantities. An incandescent filament is 'so arrangedacross the range of deflection of the element, and the reflected light beam is so directed as tg permit ready assembly of the parts, irrespeG-f tive of certain variations in the position of the mirror relative to the filament and to permit the use of a smaller casing for a given defiection of the beam.

Means is also provided whereby a plurality of characteristic curves may be photographically reproduced on one chart and readily-distinguished from each other.

Various other features are incorporated for the improvement of the device, as will hereinafter appear.

Figure l of the accompanying drawings 1s -a view, taken along the line I--I of Fig. 2, of an oscillograph constructed in accordance with my invention,

Fig. 2 is a view taken along line II-II of Fig. 1,

Fig. 3 is a front-.end elevational vlew'of the device shown in Figs. 1 and 2,

Fig. 4 is a view, taken along the line IV- IV of Fig. 2,

Fig. 5 is a detail perspective view of parts of a switch mechanism included in the device of my invention,

Fig. 6 is an enlarged detail crossssectional view, taken along a line VI-VI of Fig. 3,

lower right-hand portion of Fig. 2, as viewed in the drawings, together with a diagram of a galvanometer-lamp circuit,

Fig. 7 is a side elevational view of the device shown in Fig. 2, with a polygon of mirrors attachment in operative position thereon, p

Fig. 8 is an end elevational view, similar to Fig. 3, but having a photographic attachment in position thereon,

Fig. 9 is a diagrammatic side elevational view of a portion of the oscillograph and photographic attachment of Fig. 8,

Fig. 10 is an enlarged detail view, taken along the line X-X of Fig. 8, of a switch device employed'in connection with the device of the other figures.

Fig. 11 is a circuit diagram of certain connectionsz employed' when the instrument is emplozyed with the polygon of mirrors of Fig.

Fig. l2 is a view of a chart employed with the attachment of Figs. 8 and 9, showing curves of different circuit characteristics recorded thereon,

Fig. 13 isa circuit diagram of certain connections employed when the device is employed with photographic attachment of Figs. 8 and 9, and

Fig. 14 is a diagrammatic view of circuits and means for controlling and timing the operation of the galvanometer-lamp circuit and the particularV- circuit under test'relative to the operation of the photographic attach- ,'ment of Figs. 8 and-9.

The device of my invention comprises, in

. general, a casing 1, a galvanometer 2, a lamp 3.. a lightA shield 5, a resistor structure 6, switches 7 and 9, a device 10 that is controlled by the switches 7. and 9,l to co-operate with y reflected light beams from the galvanometer 2, and a member 11 for attaching a polygon- -of-mirrors device 12 and a lm holder 14 to the casing 1.

The casing 1 is preferably constructed .of sheet insulating material, such as fibrous material impregnated with a binder, and comprises a base plate 15, a front or face plate 17, side panels 18 and 19, atransverse vertical partition plate 21, a horizontal partition plate 22 and a, single integral or homogeneous sheet member 23 constituting the top and rear-wall members of the casing. The top and rear-wall portions of the member 23 are joined by a portion of gradual curvature for facility of manufacture,it being better practice to so round intersecting portions of certain kinds of sheet insulating material than to join -them abruptly. The portions are joined integrally to preclude the ingress of light to the casing 1 adjacent to a portion of a reflected light beam from the galvanometer 2, as will be herein. 'after pointed out.v A combined cover and name-plate member 20 is adapted for suitable mounting over an opening 24 in the member 23.

The galvanometer 2, the detail construction of which is set forth in my copending application, Serial No. 757,586, tiled Dec. 23, 1924, comprises a fluid-tight casing, disposed at thelower rear portion `of the casing 1, containing a horizontally-disposed galvanometer-mirror element 25 beneath a lens or window 26 in the upper wall of the galvanometer casing.` Terminals 27 are provided for the galvanometer element, and a structure 29 is provided to admitJ a fluid to the galvanometer casing and to adjust the tension on the galvanometer element 25, as set forth in the copend'ing application.

The lamp 3 is provided with a base or socket member 30 that is carried by a screw 31 for adjustable mounting in the side-wall plate 18 by co-operation with a nut 33 and comprises an elongated filament 34 constituting a linear light source for the galvanometer 2, for a purpose to be hereinafter described.

The light shield 5, preferably constructed of relatively thin sheet aluminum and of substantially funnel shape having rectangular cross-sectional area, is secured, at its larger end, as by screws 35, to the .horizontal partition 22 around an opening 37 in the latter. The shield 5 surrounds a portion of the reflected light beam, from the mirror 25, as indicated by a broken line 38, and projects downwardly from the partition 22 to a position just above the alvanometer 2 and beneath the lamp 3. Tis construction eX- cludes light other than the reflected beam from adjacent to the path of the beam.

A prism 39, held in position on the partition 22 over the opening 37 by members 40 and 41, is provided to direct the beam 38 from the mirror 25 through a semi-cylindrical lens 43 toward a slot 45 in the face plate 17. The member 40 is of flat strap construction and is held in position by screws 42. The member 41 is a rod of rectangular cross section having a recessed central portion 44 for positioning the prism 39 and threaded end portions 48 for the reception of terminal nuts 52. The rod 41 thus constitutes a cross brace for the casing 1, a support for the prism 39 and a connecting conductor between the panels 18 and 19, as will hereinafter be set forth.

The lens 43 is supported by a member 46 that is adjustably mounted on the partition In the above-'described system, including the lenses 26 and 43, the prism 39 and the mirror 25, the linear light source or filament 34 is disposed at one of the conjugate foci and the cylindrical lens 43 is disposed at the other.-

The parts are so arranged that, irrespective of minor discrepancies in the position of the plane of the mirror 25, a given length of the image ofthe filament 34 will always lie across the lens 43 to be condensed to substantially a point of light on the receiving surfaces of the ground-glass member 56 and on the iilm of the holder 14.

The member 11 (Fig. 3) is preferably constructed of sheet or strap material of substantially U-shape and is held in slightlyspaced parallel-planerelation to the outer surface of the face plate 17 by a spacer member 50 (Fig. 7) and screws 5,1. The arrangement of parts permits flange plates 53 (Fig. 7) and 54 (Fig. 8) of the polygon of mirrors 12 and the film holder 14, respectively, to be slipped into position behind the member 11 'to hold the polygon and film holder in proper relation to the slot 45. y

The resistor structure 6 comprises a plurality of spaced-parallel-related insulating plates 55 for the support of resistor sections 57 that are also shown diagrammatically in Figs. 11 and 13. The plates 55 are held in position by insulating members 58 that are suitably secured to the vcasing 1. Binding posts 60, on the side plates 18 and 19, are provided to connect the insulator sections and circuits as shown. in Figs. 11 and 13. As also shown in Figs. 11 and 13, conductors 64 may be connected across the casing 1, through the member 41, between the terminals on the panels 18 and 19, to facilitate a selection of proper resistor sections 57.

The switches 7 and 9 are provided with a common shaft 59, constructed of insulating material, that extends through the plates 17 and 21 and is provided, at its inner end, with a positioning sleeve 61 and, at its outer end, with an operating handle 62. An insulating cylinder 64 surrounds the insulating shaft 59 between the plates 17 and 21 and has a flattened bottom portion 68 of reduced thickness engaging the base plate 15.

The shaft 59 is journaled in the partition 21 and in a disk 63 constituting one end wall of the cylinder 64. Binding posts 65 extend radially through the side walls of the cylinder 64 and are provided with inner-end contact portions 66 for co-operation with movable contact-jaw members 67 and 69 that are mounted on the shaft 59. The jaw member 67 may be connected, through a conducting sleeve 70 on the shaft 59, a conducting clip or brush 71 and an insulated conductor 73, tothe galvanometer element 25, under certain operating conditions The brush 71 is held in position and connected to the conductor 73 by a screw 74 in the partition 21.

' The jaw members 69 are held in position on the shaft 59 and electrically `connected to each other by a conducting sleeve 75 that surrounds the shaft 59. An insulating sleeve '77 is disposed between the conducting sleeves 70 and 75 that are secured to the shaft by pins 78. e

The switch 9 comprises three annular or ring members 79, 81 and 82 that are constructed of sheet material and disposed in parallel-plane engagement with each other and with the outer surface of the disk 63. The members 79 and 82 are constructed of conducting material, such as sheet brass, and

the member 81 is of insulating material to insulate the members 79 and 82 from eachl other.

The member 79 is provided with an upper portion 83 of reduced cross-sectional area, and the members 81 and 82 are provided with upper perimetral openings 85 and 86, respectively, for a purpose to be hereinafter described.

The conducting members 79 and 82 constitute terminals of a series circuit which eX- tends from the member 79, (Fig. 6), through a conductor 87, a battery 89, a conductor 90, the lamp 3 and, through a conductor 91, to the conducting member 82.

Stationary contact buttons 93 and 94 are arranged alternately on a circle, on the front surface of the face plate 17 of the casing 1, opposite o enings 95 and 97, respectively, in the rings 79, 81 and 82. The openings 95, which, in all three of the rings 7 9, 81 and 82, are in alinement with the corresponding openings in the other rings, are relatively small in the rings 79 and 81 and relatively large in the ring 82. Similarly, the openings 97 are relatively large in the ring 79 and relatively small in the rings 81 and 82. This construction permits screw-threaded Shanks 98 on the buttons 93 to extend freely, through the openings 95 in the ring 82, into the openings 95 in the rings 81 and 79 for electric attachment to the latter. Similarly, screw threaded Shanks 99 on the buttons 94 electrically engage the ring 82 in the openings 97 thereof and extend, free of the ring 7 9, through the openings 97 thereon. The upper opening 95 in the member 79 is a clearance opening for the shank 98 of the upper button 93, the shank 98, in this instance, being utilized to secure the disk 63 to the casing 1.

With the above-described structure, a movable contact arm 101, mounted on the shaft 59 adjacent to the operating handle 62, must bridge two adjacent contact buttons 93 and 94 to complete the circuit of the lamp 3 through the battery 89. Thus, the active positions of the switch are between the buttons, as indicated by numerals 1 to 6, iii Fig. 3.

The movable arm 101 of the switch 9 is so constructed and related to the buttons 93 and 94 that only an extremely slight movement of the operating handle 62 is necessary to ining the lapproaching faces of both the but-.

tons and the arm and by having the arm a certain width, to permit the arm to seek a depressed position'between the buttons of each pair thereof. This construction serves as accentuating means for permitting the switch to be turned quickly and accurately to its closed positions and to be turned to open positions by turning the handle 62 through a wide selection of angular movement.

Referring to Figs..1, 2, 3 and 6, a cam member 102 is secured to the shaft 59, as by a pin 103, partly in an opening 105 in the face plate 17, of the casing 1, and partly in the main central openings in the ring members 79, 81 and 82 of the switch 9. An arm 106, preferably of relatively hard and durable fibrous insulating material and pivotally mounted on the screw shank of` the central upper j stationary button of the switch 9, has la dog ortion 107 for co-opera'tion with thecam 102.

he arm 106 occupies, and moves in, the space provided by the cut-away Aportion 83 of the ring 79 and the openings 85 and 86 inthe ring members81 and 82, respectively. An extension 109, preferably of sheet aluminum is secured to the arm y106, as by-screws 110, and is provided, at its upper end, with a hairlike projection 111 that is adapted' to move across the slot 45. .A spring 113, connected between one of the rivets 110 on the arm 106 and a stationary pin 114 in the front-wall plate 17 tends to' move the extension- 109 and the hair 111 in the counterclockwise direction, as viewed in Fig. 3.

Referring to Figs. 7 and 11, the polygonof-mirrors device 12 comprises a structure 115 that is mounted on a shaft 117 and is provided-with four mirror portions 118. A pul` ley 119 and a ,commutator drum 121. are mounted on the shaft 117. The latter is journaled in side-plate portions 122 that support' the ground-glass member 56 and are connected to the diange 53, above mentioned. The pulley 119-is for operation by a driving belt and a driving motorV (not shown) in a usual and well-known manner.

Referring to Figs. 8, 9 and 14, the lmholder device comprises a cylindrical sidewall member123, end-wall members 125 that are secured together against the side-wall member 123, by rods 126, and to the ange 54, a drum 127 carried by a shaft 129 that is journaled in the end-Wall members 125, a film-loading cover member 130, a set of variable-speed drive pulleys 131, and a contactmaking device 133. The drum 127 is provided therein with pivot pins 134 for the reception of .usual hlm-holding spools 135 between' which a chart or film 137 is placed over abouttwo-thirds of the outer surface of the drum 127 in the light-proof casing v formedby the side-wallA member 123 and the end-wall members 125. 4

rlfhe contact-making device 133 comprises 'an insulating member 138 mounted to rotate voltage of a circuit, the

with the shaft 129 and formed, similarly to i a worm screw, with a helical ridge 139, -between certain convolutions of which a conducting ilament or ribbon 141 is secured.

A contact member or pin 142, for engagement with the ribbon 141, is carried by a resilient arm 143 that is pivotally mounted to move about the axis of a pin 145 on a member 146 against the action of a spring 147. The latter is supported on an arm 149 that projects from a bushing or collar 150 on one of the side-wall members 125. The resilient arm 143 normallyholds the contact pin 142 out of engagement with the ribbon 141.

In operation, when it is desired to simultaneously view curves of different circuit characteristics, such as the current and the parts and circuits are arranged as shown in Figs. 7 and 11, with the polygon-of-mirrors device 12 and the -commutator drum 121 mounted on the .casing 1.

The commutator 121 comprises stationary brushes 151 and an insulated conducting segment 153 shaped to alternately shift the galvanometer element 25 from one circuit to another. In this instance, which is merely illustrative of one of several sets of circuit shifts which may be efected, the commutator, when rotated, alternatelyshifts the galvanometer element to be energized, at one time, in accordance with the current of a circuit 154 and to be energized, at the next instant,

in accordance with the voltage ofthe cir-v cuit 154. The latter is representative of a f usual circuit comprisingl a generator 155, a `current shunt 157 and a load device 158.

As illustrated in Fig. 11, the alvanometer 4element 25 is connected across t e circuit 154 conductor 161, the two-right-hand brushes 151, as viewed in the drawing, resistor sections 57 connected to terminals 60 on the panel 19 and a conductor 162. Thereafter, the galvanometer element 25 is connected across the current shunt 157 through the con-v ductor 162, certain of the resistor sections 57, the central brush 151, the segment 153, and the left-hand brush 151, to aconductor 163.

-The current through the galvanometer element 25 may be adjusted variously in accordance with the character of the circuit 154 byv proper selection of the resistor sections 57 which are to be included in circuit in the voltage and current-measuring positions of the commutator device 121. With the abovedescribedl connection. and relation of parts,

vwhich are for permitting simultaneous visualization of current and voltage waves in the mirrors 118, the switch 7 is not connected in circuit with any of the parts and the switch l9 is employed to energize the lamp by movement to any one of its closed positions.

fore the actual operation of the instrument, to compensate for time lag caused by the mechanical operation of the switch in the cirn cuit being studied.

As shown in Fig. 14, the above object is attained by providing a relay or time-controlled switch 187 having an actuating coil 189 in parallel-circuit relation to the lamp 3 for actuation by the contact-making deo vice 133.

The switch 187 "further comprises a movable core member 190 that carries an insulated bridging contact member 191 and is connected to an adjustable'dash-pot timing device 193. The latter, which may comprise a cylinder 194, an air-adjusting screw 195 and a piston 197, is for controlling the time at which the bridging contact member 191 engages stationary contact members 198. The

latter are in an auxiliary circuit 199, including a source 200 of electromotive force for energizing the closing electromagnet 201 of a circuit interrupter 202.- The latter is for closing a circuit203, including a generator 204, which is under'test. Thus, with the ar rangement of parts and circuits, as shown in Fig. 14, the circuit under test may be accurately timed for operation after t e lamp 3 comes u to brilliancy and after the active part of t e lm 137 reaches the optical slot 45. By my invention, a wide variety of circuit measurements may be taken with great facility, the size and cost of an oscillograph for' obtaining such measurements are greatly reduced and, in general, an advance in the art of investigating electrical phenomena is effected.

While I have shown and ldescribed particular forms of my invention, changes may be effected therein without departing from the spirit and scope thereof, asset forth in the appended claims.

I claim as my invention:l

1. In an oscillograph, the combination with a light-transmitting galvanometer element, of means for actuating said element in accordance with diierent quantities and for imposing a quantity distinguishing element in the path of reected light beams from the galvanometer element. l

2. In an oscillograph, the' combination with a light-transmitting galvanometer element for co-operation with a light-sensitized chart, of means for actuating said element in `accordance with different quantities and for aHecting the chart to distinguish the records.

of the dli'erent quantities.

3. In an oscillo aph, the combination with a light-transmitting galvanometer element for co-operation with a light-sensitized chart, of means for connecting said element to different circuits to be actuated thereby1 and for affectin the chart to distinguish the records of the itferent circuits.

i5 4. In an Aoscillograph, the combination 'with a light-transmitting' galvanometer element for co-operation With a light-sensitized chart, of switching means for connecting said element to different circuits to be actuated thereby, and a member normally biased toward a predetermined position and moved in response to movement of said switching means to diii'erent positions in the path of reiected light from the galvanometer element.

6. In an oscillograph, the combination with a light-transmittlng galvanometer element for co-operation with a light-sensitized chart, of means including a switch, for connecting the element to different circuits and causing the element to effect a plurality of curves on the chart, and a member actuated by the switch and o erable between the galvanometer and the c artv to cause identifying breaks in the several curves.

7. In an oscillograph, the combinationv with a light-transmitting galvanometer element for co-operation with a light-sensitized chart, of means including a switch and a plurality of impedance devices for connecting the element to different circuits and Simultaneously adjusting the element to the different circuits to effect a plurality of curves on the chart, and a member actuated /by the switch ando erable between the galvanometer and the chart to cause identifying breaks in the several curves. l 8. The combination with a light-reflecting alvanometer element, and a lamp, ofv swltching means for connecting the element to' different circuits and means responsive to thev movement of said switching means for energizing the lamp after making, and de-energizing the'lamp beforel breaking, the connection of the element to each circuit.

9. The combination with a light-reiiectingalvanometer element, and a lamp, of switchlng means for connecting the element to( different kcircuits and for vdisconnecting the lamp in response vto a change in theconnection of the' element from one circuit to another.- A

' 10. The combination with a galvanometer including a light-reflecting element and a lamp therefor, of means comprising a unilamp therefor, of means for successively connecting the galvanometer to different circuits and for energizing the lamp only during the connection of the galvanometer to one of said circuits comprising a switch for the galvanometer including a movable contact member and stationary contact members spaced to permit entire separation between each thereof and said movable contact member, a second switch for the lamp including a movable contact member and stationary contact members spaced to permit the movable contact member to bridge the adjacent stationary contact members, and a single operating member for said switches.

12. In combination, a source of light, a relatively movable light-sensitized member, and control means for said light source for temporarily impressing an excess voltage on said source, said control mean-s being operative a predetermined time interval before eX- posure yof said member t0 the light from said source.

13. In combination, a source of light requiring a predetermined time interval to attain full brilliancy, a light-sensitized member movable relative thereto, said member being mounted on a rotatable drum, and means for energizing said source and for automatically exposing said member to light therefrom when the source attains a predetermined brilliancy.

14. In combination, a source of light requiring a predetermined time interval to attain full brilliancy, a light-sensitized member movable relative thereto, said member being mounted on a rotatable drum, and means having predetermined relation to movement of said member for energizing said source and for automatically exposing said member to light therefrom a predetermined time interval after the energization of said source.

15. In combination, a source of light, a relatively rotatable member upon which a light-sensitized element is supported and means having a predetermined relation to movement of said member for temporarily energizing said source by an'excess voltage.

16. In combination, a source of light, a relatively rotatable member `upon which a light-sensitized element is su ported and means having a predetermined) relation to movement of said member for temporarily energizing said source by an excess voltage during a predetermined movement of said member.

17. In combination, a rotatable drum for the reception around a portion only of the cylindrical surface thereof of a sheet of lightsensitized material, an electric lamp, means for directing light from said lamp toward a point on sai-d drum, and means controlled by movement of the drum for automatically initially energizing said lamp before said sensitized sheet is oppositesaid point to have the lamp at full brilliancy just before the sensitized sheet starts to rotate by said point.

18. Electrical indicating apparatus comprising a straight-line source of light, means including a mirror for vibrating, in accordance with a varying electrical quantity, a beam of light supplied by said source, a converging spherical lens so positioned between said source and said mirror that said beam passes therethrough to said mirror and is reflected to again pass therethrough, and a cylindrical condensing lens positioned transversely of the path of said reflected beam.

In testimony whereof, I have hereunto subscribed my name this 25th day of November,

JOSEPH W. LEGG. 

